Electroluminescence display

ABSTRACT

An electroluminescence display can include a substrate including a first pixel at a first row and a first column, a second pixel at the first row and a second column, a third pixel at a second row and the first column, and a fourth pixel at the second row and the second column, a first vertical trench between the first pixel and the second pixel, a second vertical trench between the third pixel and the fourth pixel, a first horizontal trench between the first pixel and the third pixel, a second horizontal trench between the second pixel and the fourth pixel, and a protrusion pillar at an intersection portion of the substrate where the first vertical trench, the second vertical trench, the first horizontal trench, and the second horizontal trench converge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to the Korean PatentApplication No. 10-2021-0183982 filed in the Republic of Korea on Dec.21, 2021, the entire contents of which are hereby expressly incorporatedby reference into the present application.

BACKGROUND OF THE DISCLOSURE Field of the Invention

The present disclosure relates to an electroluminescence display. Inparticular, the present disclosure relates to an electroluminescencedisplay having a structure that prevents or reduces the lateral (orhorizontal) leakage current occurring between neighboring pixels in theultra-high resolution of pixel array.

Discussion of the Related Art

Recently, various type of display have been developed, such as thecathode ray tubes (CRTs), the liquid crystal displays (LCDs), the plasmadisplay panels (PDPs) and the electroluminescent displays. These varioustypes of display can be used to display image data of various productssuch as computer, mobile phones, bank deposit and withdrawal devices(ATMs), and vehicle navigation systems according to their specificcharacteristics and purposes.

In particular, the electroluminescent display is a self-luminousdisplay, and has a structure in which a plurality of pixel areasincluding light emitting diodes are arranged. As the density of pixelsincreases, the distance between pixels becomes closer, and thedistortion of pixel information can occur due to the lateral leakagecurrent between pixels adjacent to each other in the lateral (orhorizontal) direction. In order to ensure excellent display quality, itis necessary to develop a structure for an electroluminescence displaythat is capable of suppressing a lateral leakage current betweenneighboring pixels.

SUMMARY OF THE DISCLOSURE

An object to be achieved by embodiments of the present disclosure is toprovide an electroluminescence display capable of preventing or reducingdisplay quality degradation due to the leakage current in a lateraldirection as a distance between pixels in a display device having a highpixel density becomes narrower. In particular, the purpose of thepresent disclosure is to prevent or reduce image quality distortion byforming a trench surrounding all sides of the pixel in a plane view toblock the lateral leakage current in longitudinal direction andtransverse direction. Another purpose of the present disclosure is toprevent or reduce leakage current generated as the width of the trenchincreases in a portion where a horizontal trench extending along ahorizontal direction and a vertical trench extending along a verticaldirection are intersected.

In order to accomplish the above mentioned purposes of the embodimentsof the present disclosure, an electroluminescence display according tothe present disclosure can include a first pixel disposed at 1st row-1stcolumn, a second pixel disposed at 1st row-2nd column, a third pixeldisposed at 2nd row-1st column, and a fourth pixel disposed at 2ndrow-2nd column on a substrate; a first vertical trench disposed betweenthe first pixel and the second pixel; a second vertical trench disposedbetween the third pixel and the fourth pixel; a first horizontal trenchdisposed between the first pixel and the third pixel; a secondhorizontal trench disposed between the second pixel and the fourthpixel; and a protrusion pillar disposed at an intersection portion wherethe first vertical trench and the second vertical trench face, and thefirst horizontal trench and the second horizontal trench face.

In one embodiment of the present disclosure, the electroluminescencedisplay can further include a first emission layer disposed at the firstpixel to the fourth pixel, disconnected by the first vertical trench,the second vertical trench, the first horizontal trench and the secondhorizontal trench, and connected passing over the protrusion pillar; acharge generation layer disposed on the first emission layer,disconnected by the first vertical trench, the second vertical trench,the first horizontal trench and the second horizontal trench, andconnected passing over the protrusion pillar; and a second emissionlayer on the charge generation layer, and connected passing over thefirst vertical trench, the second vertical trench, the first horizontaltrench, the second horizontal trench, and the protrusion pillar.

In one embodiment, the electroluminescence display can further include aplurality of first electrodes, each of the first electrode disposing atfirst pixel to fourth pixel; and a second electrode disposed on thesecond emission layer, and connected passing over the first verticaltrench, the second vertical trench, the first horizontal trench, thesecond horizontal trench, and the protrusion pillar.

In one embodiment, the protrusion pillar has a rectangular shapeincluding four sides corresponding to a width of the first verticaltrench, the second vertical trench, the first horizontal trench and thesecond horizontal trench.

In one embodiment, the protrusion pillar is a ‘+’ shaped pillar havingprotruding lengths from the rectangular shape in directions of the firstvertical trench, the second vertical trench, the first horizontal trenchand the second horizontal trench.

In one embodiment, a ratio of the protruding length in the direction ofthe first vertical trench from the rectangular shape and a length of thefirst vertical trench has any one value selected from 1:8 to 0:10. Aratio of the protruding length in the direction of the first horizontaltrench from the rectangular shape and a length of the first horizontaltrench has any one value selected from 1:8 to 0:10.

In addition, an electroluminescence display according to the presentdisclosure can include a substrate; a planarization layer on a wholesurface of the substrate; a first electrode disposed on theplanarization layer and including a first side, a second sideperpendicular to the first side, and an intersection portionintersecting the first side and the second side; a trench disposed atoutside of the first side and the second side, and having apredetermined width; a protrusion pillar disposed at the intersectionportion; a first emission layer disposed on the first electrode,disconnected by the trench, and connected passing over the protrusionpillar; a charge generation layer disposed on the first emission layer,disconnected by the trench, and connected passing over the protrusionpillar; a second emission layer disposed on the charge generation layer,connected passing over the trench, and connected passing over theprotrusion pillar; and a second electrode disposed on the secondemission layer, connected passing over the trench and the pillar.

In one embodiment, the charge generation layer is electricallydisconnected from the cathode electrode.

In one embodiment, the first electrode further includes a third sideparallel to the first side; and a fourth side parallel to the secondside. The trench includes a first trench disposed outside the first sideand the third side; and a second trench disposed outside the second sideand the fourth side.

In one embodiment, the electroluminescence display can further include abank covering the first side, the second side, the third side and thefourth side of the first electrode, and exposing a central portion ofthe first pixel. The trench is formed by removing the bank and theplanarization layer with a predetermined depth.

In one embodiment, the protrusion pillar is formed on an upper surfaceof the bank disposed at the intersection portion.

In one embodiment, the bank includes a first bank; and a second bankdisposed on the first bank.

In one embodiment, the trench includes a first trench disposed outsidethe first side and corresponding to the first side; a second trenchdisposed outside the second side and corresponding to the second side; athird trench disposed outside the third side and corresponding to thethird side; and a fourth trench disposed outside the fourth side andcorresponding to the fourth side. The protrusion pillar includes foursides corresponding to the width of the trench at the intersectionportion.

In one embodiment, the protrusion pillar has a ‘+’ shaped pillarprotruding toward the first side and the second side from theintersection portion.

In one embodiment, a ratio of (a first protrusion length protruding fromthe protrusion pillar disposed at one end of the first horizontal trenchtoward the first horizontal trench) : (a length of the first horizontaltrench) : (a second protrusion length protruding from the protrusionpillar PRL disposed at the other end of the first horizontal trenchtoward the first horizontal trench) has any one of 1:8:1 to 0:10:0.

The electroluminescent display according to the present disclosureincludes a trench structure surrounding each pixel in a plane view. Inparticular, a vertical trench running in a longitudinal direction and ahorizontal trench running in a transverse direction are provided.Therefore, the charge generation layer of the organic emission layerstacked on the entire surface of the substrate can have a structure inwhich electrical connectivity is disconnected in a transverse (orhorizontal) direction and a longitudinal (or vertical) direction in aplane view. As a result, image distortion due to the lateral leakagecurrent between neighboring pixels can be prevented or reduced. In thetrench arrangement having the net structure as described above, thewidth of the trench can be wide at the intersection portion. At theintersection portion where the trench width is wider than otherportions, the charge generation layer of the organic emission layer canbe connected to the cathode electrode, so that a pixel defect can occur.However, in the present disclosure, since the barrier rib structure isformed at the intersection of the trench arrangement, the chargegeneration layer of the organic emission layer can have a structure ofhigh electrical resistance between neighboring pixels. Accordingly, itis possible to provide excellent image information by blocking lateralleakage current in all directions in the electroluminescence displayhaving an ultra-high resolution structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a plane view illustrating a schematic structure of anelectroluminescence display according to an embodiment of the presentdisclosure.

FIG. 2 is a circuit diagram illustrating a structure of one pixelaccording to an embodiment of the present disclosure.

FIG. 3 is a plan view illustrating a structure of 2X2 pixels in theelectroluminescence display according to a first embodiment of thepresent disclosure.

FIG. 4 is a cross-sectional view along to cutting line I-I′ in FIG. 3 ,for illustrating the structure of the electroluminescence displayaccording to the first embodiment of the present disclosure.

FIG. 5 is an enlarged cross-sectional view illustrating a structure ofpart ‘A’ indicated by a dotted rectangle in FIG. 4 .

FIG. 6 is a cross-sectional view illustrating a structure of anelectroluminescence display according to the first embodiment of thepresent disclosure.

FIG. 7 is a plane view illustrating a structure of trench disposedbetween 2×2 pixels in an electroluminescence display according to thefirst embodiment of the present disclosure.

FIG. 8 is a cross-sectional view along to cutting line II-II′ in FIG. 7, for illustrating a structure of an electroluminescence displayaccording to the first embodiment of the present disclosure.

FIG. 9 is a plane view illustrating a structure of 2×2 pixels in theelectroluminescence display according to a second embodiment of thepresent disclosure.

FIG. 10 is a cross-sectional view along to cutting line III-III′ in FIG.9 , for illustrating a structure of an electroluminescence displayaccording to the second embodiment of the present disclosure.

FIG. 11 is a plane view illustrating a structure of 2×2 pixels in theelectroluminescence display according to a third embodiment of thepresent disclosure.

FIG. 12 is a cross-sectional view illustrating a structure of anelectroluminescence display according to a fourth embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Advantages and features of the embodiments of present disclosure, andimplementation methods thereof will be clarified through followingembodiments described with reference to the accompanying drawings. Thepresent disclosure may, however, be embodied in different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the presentdisclosure to those skilled in the art. Further, the present disclosureis only defined by scopes of claims.

A shape, a size, a ratio, an angle, and a number disclosed in thedrawings for describing embodiments of the present disclosure are merelyan example, and thus, the present disclosure is not limited to theillustrated details. Like reference numerals refer to like elementsthroughout. In the following description, when the detailed descriptionof the relevant known function or configuration is determined tounnecessarily obscure the important point of the present disclosure, thedetailed description will be omitted.

Reference will now be made in detail to the example embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.In the specification, it should be noted that like reference numeralsalready used to denote like elements in other drawings are used forelements wherever possible. In the following description, when afunction and a configuration known to those skilled in the art areirrelevant to the essential configuration of the present disclosure,their detailed descriptions will be omitted. The terms described in thespecification should be understood as follows.

In the instance that “comprise,” “have,” and “include” described in thepresent specification are used, another part can also be present unless“only” is used. The terms in a singular form can include plural formsunless noted to the contrary.

In construing an element, the element is construed as including an errorrange or a reasonable range although there may not be an explicitdescription.

In describing a positional relationship, for example, when thepositional order is described as “on,” “above,” “below,” and “next,” theinstance of no contact there-between can be included, unless “just” or“direct” is used. If it is mentioned that a first element is positioned“on” a second element, it does not necessarily mean that the firstelement is essentially positioned above the second element in thefigure. The upper part and the lower part of an object concerned can bechanged depending on the orientation of the object. Consequently, theinstance in which a first element is positioned “on” a second elementincludes the instance in which the first element is positioned “below”the second element as well as the instance in which the first element ispositioned “above” the second element in the figure or in an actualconfiguration.

In describing a temporal relationship, for example, when the temporalorder is described as “after,” “subsequent,” “next,” and “before,” aninstance which is not continuous can be included, unless “just” or“direct” is used.

It will be understood that, although the terms “first,” “second,” etc.,can be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure.

In describing the elements of the present disclosure, terms such as thefirst, the second, A, B, (a) and (b) can be used. These terms are onlyto distinguish the elements from other elements, and the terns are notlimited in nature, order, sequence or number of the elements. When anelement is described as being “linked”, “coupled” or “connected” toanother element that element can be directly connected to or connectedto that other element, but indirectly unless otherwise specified. It isto be understood that other elements can be “interposed” between eachelement that can be connected to or coupled to.

It should be understood that the term “at least one” includes allcombinations related with any one item. For example, “at least one amonga first element, a second element and a third element” can include allcombinations of two or more elements selected from the first, second andthird elements as well as each element of the first, second and thirdelements.

Features of various embodiments of the present disclosure can bepartially or overall coupled to or combined with each other, and can bevariously inter-operated with each other and driven technically as thoseskilled in the art can sufficiently understand. The embodiments of thepresent disclosure can be carried out independently from each other, orcan be carried out together in a co-dependent relationship.

Hereinafter, an example of a display apparatus according to the presentdisclosure will be described in detail with reference to theaccompanying drawings. In designating reference numerals to elements ofeach drawing, the same components can have the same reference numeralsas much as possible even though they are shown in different drawings.Scale of the elements shown in the accompanying drawings can have adifferent scale from the actual for convenience of description, and eachelement is not limited to the scale shown in the drawings.

Hereinafter, referring to attached figures, an explanation about thepresent disclosure is provided in detail. FIG. 1 is a diagramillustrating a schematic structure of an electroluminescence displayaccording to the present disclosure. In FIG. 1 , X-axis can be parallelto the extending direction of the scan line, Y-axis can be parallel tothe extending direction of the data line, and Z-axis can represent thethickness direction of the display. All components of eachelectroluminescence emitting display according to all embodiments of thepresent disclosure are operatively coupled and configured.

Referring to FIG. 1 , the electroluminescence display can include asubstrate 110, a gate (or scan) driver 200, a data pad portion 300, asource driving IC (Integrated Circuit) 410, a flexible film 430, acircuit board 450, and a timing controller 500.

The substrate 110 can include an electrical insulating material or aflexible material. The substrate 110 can be made of a glass, a metal ora plastic, but it is not limited thereto. When the electroluminescencedisplay is a flexible display, the substrate 110 can be made of theflexible material such as plastic. For example, the substrate 110 caninclude a transparent polyimide material.

The substrate 110 can include a display area DA and a non-display areaNDA. The display area DA, which is an area for representing ordisplaying the video images, can be defined as the majority middle areaof the substrate 110, but it is not limited thereto. In the display areaDA, a plurality of scan lines (or gate lines), a plurality of data linesand a plurality of pixels P1, P2, P3 and P4 can be formed or disposed.Each of pixels can include a plurality of sub pixels. Each of sub pixelscan include the scan line and the data line, respectively.

The non-display area NDA, which is an area not representing ordisplaying the video images, can be defined at the circumference areasof the substrate 110 surrounding all or some of the display area DA. Inthe non-display area NDA, the gate driver 200 and the data pad portion300 can be formed or disposed therein.

The gate driver 200 can supply the scan (or gate) signals to the scanlines according to the gate control signal received from the timingcontroller 500. The gate driver 200 can be formed at the non-displayarea NDA at any one outside of the display area DA on the substrate 110,as a GIP (Gate driver In Panel) type. GIP type means that the gatedriver 210 is directly formed on the substrate 110.

The data pad portion 300 can supply the data signals to the data lineaccording to the data control signal received from the timing controller500. The data pad portion 300 can be made as a driver chip and mountedon the flexible film 430. Further, the flexible film 430 can be attachedat the non-display area NDA at any one outside of the display area DA onthe substrate 110, as a TAB (Tape Automated Bonding) type.

The source driving IC 410 can receive the digital video data and thesource control signal from the timing controller 500. The source drivingIC 410 can convert the digital video data into the analog data voltagesaccording to the source control signal and then supply that to the datalines. When the source driving IC 410 is made as a chip type, it can beinstalled on the flexible film 430 as a COF (Chip On Film) or COP (ChipOn Plastic) type.

The flexible film 430 can include a plurality of first link linesconnecting the data pad portion 300 to the source driving IC 410, and aplurality of second link lines connecting the data pad portion 300 tothe circuit board 450. The flexible film 430 can be attached on the datapad portion 300 using an anisotropic conducting film, so that the datapad portion 300 can be connected to the first link lines of the flexiblefilm 430.

The circuit board 450 can be attached to the flexible film 430. Thecircuit board 450 can include a plurality of circuits implemented as thedriving chips. For example, the circuit board 450 can be a printedcircuit board or a flexible printed circuit board.

The timing controller 500 can receive the digital video data and thetiming signal from an external system board through the line cables ofthe circuit board 450. The timing controller 500 can generate a gatecontrol signal for controlling the operation timing of the gate driver200 and a source control signal for controlling the source driving IC410, based on the timing signal. The timing controller 500 can supplythe gate control signal to the gate driver 200 and supply the sourcecontrol signal to the source driving IC 410. Depending on the producttypes, the timing controller 500 can be formed as one chip with thesource driving IC 410 and mounted on the substrate 110.

First Embodiment

Hereinafter, referring to FIGS. 2 to 4 , an electroluminescence displayaccording to the first embodiment of the present disclosure will beexplained. FIG. 2 is a circuit diagram illustrating a structure of onepixel according to the present disclosure. FIG. 3 is a plan viewillustrating a structure of 2×2 pixels in the electroluminescencedisplay according to the first embodiment of the present disclosure.FIG. 4 is a cross-sectional view along to cutting line I-I′ in FIG. 3 ,for illustrating the structure of the electroluminescence displayaccording to the first embodiment of the present disclosure.

Referring to FIGS. 2 to 4 , one-pixel P of the light emitting displaycan be defined by a scan line SL, a data line DL and a driving currentline VDD. One pixel of the light emitting display can include aswitching thin film transistor ST, a driving thin film transistor DT, alight emitting diode OLE and a storage capacitance (or storagecapacitor) Cst. The driving current line VDD can be supplied with ahigh-level voltage for driving the light emitting diode OLE.

For example, the switching thin film transistor ST can be disposed atthe portion where the scan line SL and the data line DL is crossing. Theswitching thin film transistor ST can include a switching gate electrodeSG, a switching source electrode SS and a switching drain electrode SD.The switching gate electrode SG can be connected to the scan line SL.The switching source electrode SS can be connected to the data line DLand the switching drain electrode SD can be connected to the drivingthin film transistor DT. By supplying the data signal to the drivingthin film transistor DT, the switching thin film transistor ST can playa role of selecting a pixel which would be driven.

The driving thin film transistor DT can play a role of driving the lightdiode OLE of the selected pixel by the switching thin film transistorST. The driving thin film transistor DT can include a driving gateelectrode DG, a driving source electrode DS and a driving drainelectrode DD. The driving gate electrode DG can be connected to theswitching drain electrode SD of the switching thin film transistor ST.For example, the switching drain electrode SD can be connected to thedriving gate electrode DG via the drain contact hole DH penetrating thegate insulating layer GI. The driving source electrode DS can beconnected to the driving current line VSS, and the driving drainelectrode DD can be connected to an anode electrode ANO of the lightemitting diode OLE. A storage capacitance Cst can be disposed betweenthe driving gate electrode DG of the driving thin film transistor DT andthe anode electrode ANO of the light emitting diode OLE.

The driving thin film transistor DT can be disposed between the drivingcurrent line VDD and the light emitting diode OLE. The driving thin filmtransistor DT can control the amount of electric currents flowing to thelight emitting diode OLE from the driving current line VDD according tothe voltage level of the driving gate electrode DG connected to theswitching drain electrode SD of the switching thin film transistor ST.

The light emitting diode OLE can include an anode electrode ANO, anemission layer EL and a cathode electrode CAT. The light emitting diodeOLE can emit the light according to the amount of the electric currentcontrolled by the driving thin film transistor DT. In other word, thelight emitting diode OLE can be driven by the voltage differencesbetween the low-level voltage and the high-level voltage controlled bydriving thin film transistor DT.

The passivation layer PAS can be deposited on the top surface of thesubstrate 110 having the thin film transistors ST and DT. By example,the passivation layer PAS is made of inorganic material such as siliconoxide (SiOx) or silicon nitride (SiNx). The color filter CF can beformed on the passivation layer PAS. By example, the color filter CF canbe disposed as fully overlapping with the anode electrode ANO which canbe formed later.

The planarization layer PL can be deposited on the passivation layer PASand the color filter CF. The planarization layer PL can be the filmlayer for flattening the non-uniform surface of the substrate 110 onwhich the thin film transistors ST and DT are formed. In order to makethe even surface condition of the substrate 110, the planarization layerPL can be formed of an organic material. The passivation layer PAS andthe planarization layer PL can include the pixel contact hole PHexposing some portions of the driving drain electrode DD of the drivingthin film transistor DT.

The anode electrode ANO can be formed on the planarization layer PL. Theanode electrode ANO can be connected to the driving drain electrode DDof the driving thin film transistor DT through a pixel contact hole PHformed at the planarization layer PL. The anode electrode ANO can havevarious structures and different materials according to the emissiontype of the organic light emitting diode OLE. For an example, for thebottom emission type in which the light can be provided to the substrate110 direction from the emission layer EL, the anode electrode ANO can bemade of a transparent conductive material. For example, the anodeelectrode ANO of the bottom emission type can include an oxideconductive material such as indium-zinc-oxide (or IZO) orindium-tin-oxide (or ITO). For another example, for the top emissiontype in which the light can be provided to the upper direction oppositethe substrate 110, the anode electrode ANO can be made of metalmaterials having excellent or predetermined light reflectance. FIG. 4shows the structure of the bottom emission type, the present disclosurecan be applicable to the top emission type.

A bank BA can be formed on the anode electrode ANO. The bank BA cancover the circumference areas of the anode electrode ANO and can exposemost of middle areas of the anode electrode ANO. The middle areas of theanode electrode ANO exposed by the bank BA can be defined the emissionarea.

The trench TR can be disposed between the pixels formed by removing someportions of the bank BA and the planarization layer PL. The trench TRcan include a horizontal trench TRH and a vertical trench TRV. Thehorizontal trench TRH can extend along the X-axis direction ortransverse direction in a plane view on the substrate 110. The verticaltrench TRV can extend along the Y-axis direction or longitudinaldirection in a plane view on the substrate 110. One vertical trench TRVcan be disposed at the left side and the right side of the pixel, andone horizontal trench TRH can be disposed at the upper side and thelower side of the pixel.

An emission layer EL can be deposited on the bank BA and the anodeelectrode ANO. The emission layer EL can be deposited over the wholesurface of the display area DA on the substrate 110, as covering theanode electrodes ANO and banks BA. For an example, the emission layer ELcan include two or more stacked emission portions for emitting whitelight. In detail, the emission layer EL can include a first emissionlayer providing first color light and a second emission layer providingsecond color light, for emitting the white light by combining the firstcolor light and the second color light. In this instance, a chargegeneration layer CG can be disposed between the first emission layer E1and the second emission layer E2. The first emission layer E1, which isdisposed between the anode electrode ANO and the charge generation layerCG, can emit the first color light. The second emission layer E2, whichis disposed between the charge generation layer CG and the cathodeelectrode CAT, can emit the second color light.

The cathode electrode CAT can be disposed on the emission layer EL. Thecathode electrode CAT can be stacked on the emission layer EL as beingin surface contact with the second emission layer E2. The cathodeelectrode CAT can be formed as one sheet element over the whole area ofthe substrate 110 as being commonly connected whole emission layers ELdisposed at all pixels. In the instance of the bottom emission type, thecathode electrode CAT can include metal material having excellent lightreflection ratio. For example, the cathode electrode CAT can include atleast any one of silver (Ag), aluminum (Al), molybdenum (Mo), gold (Au),magnesium (Mg), calcium (Ca), or barium (Ba).

Hereinafter, referring to FIG. 5 , the structure for cutting theelectric connection between the pixels by the trench will be described.FIG. 5 is an enlarged cross-sectional view illustrating a structure ofpart ‘A’ indicated by a dotted rectangle in FIG. 4 .

The gate insulating layer GI is deposited on the substrate 110. Thedriving current line VDD and the data line DL are formed on the gateinsulating layer GI. The passivation layer PAS is deposited on thedriving current line VDD and the data line DL. The color filter CF isdeposited on the passivation layer PAS. For example, between anyneighboring two pixels, a red color filter can be formed at the leftpixel and a green color filter can be formed at the right pixel.

The planarization layer PL is deposited on the color filter CF. Theanode electrode ANO is formed on the planarization layer PL. The bank BAis formed on the anode electrode ANO as covering circumference areas ofthe anode electrode ANO. Between two neighboring pixels, the trench TRis disposed. The trench TR can be formed by etching some portions of thebank BA and the planarization layer PL with a predetermined depth. Theetched portions can be disposed between two neighboring anode electrodesANO. FIG. 5 illustrates, for convenience, only the structure of thevertical trench TRV disposed between the driving current line VDD andthe data line DL, the horizontal trench TRH can also have the samestructure.

The trench TR can include a well structure having a bottom surface 10and the side-wall surface 20. With the trench TR, the first emissionlayer E1 can be deposited on the anode electrode ANO and the bank BA. Asthe result, the first emission layer E1 can be deposited on the bottomsurface 10 of the trench TR. However, on the side-wall surface 20, thefirst emission layer E1 need not be fully deposited, but it can bepartially deposited at the top portions of the trench TR. For example,the first emission layer E1 can be deposited on the surface of thesubstrate 110, but the electrical connection of the first emission layerE1 can be cut, so that it can be separated in a pixel unit.

The charge generation layer CG can be deposited on the first emissionlayer E1. On the bottom surface 10 of the trench TR, the chargegeneration layer CG can be deposited on the first emission layer E1. Onthe side-wall surface 20, the charge generation layer CG can bepartially deposited at the top portions. For example, the stacked shapeof the charge generation layer CG can have a shape as covering someportions of the first emission layer E1. In some instances, the chargegeneration layer CG can cover the whole of the first emission layer E1.The charge generation layer CG can be deposited on the surface of thesubstrate 110, but the electrical connection of the charge generationlayer CG can be cut, so that it can be separated in a pixel unit.

The second emission layer E2 is deposited on the charge generation layerCG. The top portions of the trench TR is in a state in which a width ofthe trench TR is narrowed due to the previously stacked profile of thefirst emission layer E1 and the charge generation layer CG. Under thiscondition, as the deposition process of the second emission layer E2 isperformed, the second emission layer E2 becoming increasingly thickerfrom the left side and the second emission layer E2 becomingincreasingly thicker from the right side can contact each other at thetop portion of the trench TR. Thus, a cross sectional shape (or profile)of the top space of the trench TR can be filled or closed. As theresult, the second emission layer E2 can have a structure in which thesecond emission layer E2 can be connected over all pixels on the wholesurface of the substrate 110. Further, the second emission layer E2 neednot be deposited within the trench TR. However, according to the depthor the height of the trench TR, some portions of the second emissionlayer E2 can be disconnected by the trench TR.

After that, the cathode electrode CAT is deposited on the secondemission layer E2. Since the second emission layer E2 has a structureconnected between all pixels on the entire surface of the substrate 110,the cathode electrode CAT also has a structure connected between allpixels. An encapsulation layer can be deposited on the cathode electrodeCAT.

With the structure as shown in FIG. 5 , the first emission layer E1deposited just on the anode electrode ANO can include a hole transportlayer. Since the first emission layer E1 is divided for each pixel bythe trench TR, a problem in which charges move between neighboringpixels through the charge transport layer can be prevented or reduced.In addition, since the charge generation layer CG stacked on the firstemission layer E1 is also divided in pixel units by the trench TR, theproblem in which charges move between neighboring pixels through thecharge generation layer CG can be prevented or reduced.

The second emission layer E2 can include an electron transport layer. Byexample, the electron transport layer can be a common layer connectedover all pixels, like the cathode electrode CAT. Even though theelectrons can move between neighboring pixels through the electrontransport layer, the flow of the holes can be blocked betweenneighboring pixels due to the trench TR. Therefore, there is no problemof the display quality due to the lateral leakage current.

With FIGS. 4 and 5 , explained is the bottom emission typeelectroluminescence display having the structure for suppressing thelateral leakage current by the trench according to the first embodiment.The features of the present disclosure can be applied to the topemission type electroluminescence display as shown in FIG. 6 . FIG. 6 isa cross-sectional view illustrating a structure of anelectroluminescence display according to the first embodiment of thepresent disclosure.

Referring to FIG. 6 , the electroluminescence display according toanother example of the first embodiment can include a substrate, acircuit element layer, a planarization layer PL, a first electrode ANO,an emission layer EL, a second electrode CAT, a bank BA, anencapsulation layer ENC, a first color filter CFR, a second color filterCFG and a third color filter CFB. The substrate and circuit elementlayer can be the same with substrate 110 and thin film transistors STand DT explained above, so the explanation for these elements may not beduplicated.

The electroluminescence display shown in FIG. 6 can have a top emissionstructure in which the light from the emission layer can be emitted tothe upward direction opposite the substrate. Therefore, the substratecan be made of transparent material or an opaque material.

The planarization layer PL can be deposited on the circuit elementlayer. The planarization layer PL can be made of an organic materialsuch as acryl resin, epoxy resin, phenolic resin, polyamide resin andpolyimide resin. Otherwise, the planarization layer PL can be made of aninorganic material such as silicon nitride, aluminum nitride, zirconiumnitride, titanium nitride, hafnium nitride, tantalum nitride, siliconoxide, aluminum oxide or titanium oxide.

The planarization layer PL can have the trench TR disposed at the borderarea between the first sub-pixel P1 and the second sub-pixel P2 and atthe border area between the second sub-pixel P2 and the third sub-pixelP3. The trench TR can be disposed at an area between the bank BAcovering the end of the first electrode ANO of the first sub-pixel P1and the bank BA covering the end of the first electrode ANO of thesecond sub-pixel P2, and at an area between the bank BA covering the endof the first electrode ANO of the second sub-pixel P2 and the bank BAcovering the end of the first electrode ANO of the third sub-pixel P3.The trench TR can be dug into a predetermined region inside theplanarization layer PL without penetrating the planarization layer PL.However, it is not limited thereto. The trench TR can pass through theplanarization layer PL and can extend into a predetermined region insidethe circuit element layer below the planarization layer PL in otherembodiments.

The bank BA can be formed at the boundary area between the adjacentsub-pixels P1 to P3 in a matrix structure. One end of the bank BA can bedisposed to be in contact with the entrance (or upper aperture) of thetrench TR, or can be spaced apart from the entrance of the trench TR bya predetermined distance. The bank BA can be formed as covering both endportions of the first anode electrode disposed at the first to thirdsub-pixels P1 to P3. Therefore, the exposed portion of the firstelectrode ANO not covered by the bank BA can be defined as the emissionarea.

The emission layer EL can be formed on the bank BA and the firstelectrode ANO. For example, the emission layer EL can be formed ascovering the boundary areas of the adjacent sub-pixels P1 to P3. Theemission layer EL can be configured to emit white light. In thisinstance, the emission layer EL can include a plurality of stacks thatemit light of different colors. For example, the emission layer EL caninclude a first stack 421, a second stack 423 and a charge generationlayer (or CGL) 422 provided between the first stack 421 and the secondstack 423.

For example, the first stack 421 can include a hole injection layer, afirst hole transport layer, a first organic emission layer and a firstelectron transport layer sequentially stacked. The second stack 423 caninclude a second hole transport layer, a second organic emission layer,a second electron transport layer and an electron injection layersequentially stacked. The charge generation layer 422 can include aN-type charge generation layer supplying electrons to the first stack421 and a P-type charge generation layer supplying holes to the secondstack 423.

The emission layer EL can be formed inside the trench TR and on thetrench TR. When the emission layer EL is disposed inside the trench TR,the emission layer EL or portions can be disconnected between theneighboring two sub-pixels, so the leakage current between the adjacentsub-pixels P1 to P3 can be prevented or reduced. At the disconnection ofthe emission layer EL, the portions of the emission layer EL that aredisconnected can have tapered ends with reduced thicknesses.

In detail, the first stack 421 can be disposed on an inside wall and abottom surface of the trench TR. Here, the first stack 421 can bedisconnected without being continuous over the trench TR. Therefore, theelectric carriers need not flow through the first stack 421 between thefirst sub-pixel P1 and the second sub-pixel P2 and between the secondsub-pixel P2 and the third sub-pixel P3 which are adjacent each otherwith the trench TR interposed there-between.

The charge generation layer 422 can be deposited on the first stack 421.Here, the charge generation layer 422 can be disconnected at the insideof the trench TR or a region overlapping the trench TR. Therefore, theelectric carriers need not flow through the charge generation layer 422between the first sub-pixel P1 and the second sub-pixel P2 and betweenthe second sub-pixel P2 and the third sub-pixel P3 which are adjacenteach other with the trench TR interposed there-between. At thedisconnection of the charge generation layer 422, the portions of thecharge generation layer 422 can have a tapered end with reducedthicknesses.

The second stack 423 can be deposited on the charge generation layer422. Here, the second stack 423 can be continuously disposed between thefirst sub-pixel P1 and the second sub-pixel P2 and between the secondsub-pixel P2 and the third sub-pixel P3 which are adjacent each otherwith the trench TR interposed there-between. In some instances, thesecond stack 423 can be disconnected at some portions by the trench TRbut can be connected at other portions over the trench TR. Therefore,the electric carriers can flow through the second stack 423 between thefirst sub-pixel P1 and the second sub-pixel P2 and between the secondsub-pixel P2 and the third sub-pixel P3 which are adjacent each otherwith the trench TR interposed there-between.

Due to the above-mentioned structures of the first stack 421, the chargegeneration layer 422 and the second stack 423, an empty gap (or void) Gcan be provided in the emission layer EL. In detail, the void G can beformed inside the trench TR and can extend over the trench TR. Here, theupper end of the void G can be located at the higher position than thecharge generating layer 422, so that the charge generation layer 422 canbe disconnected by the void G at the trench TR. In addition, the widthof the void G can be gradually narrowed from the bottom of the void G tothe top of the void G.

The second electrode CAT can be formed on the second stack 423. Thesecond electrode CAT can be the cathode electrode of the display. Thesecond electrode CAT can be deposited over the sub-pixels P1 to P3 andthe boundary areas between the sub-pixels P1 to P3. Since the uppersurface of the second stack 423 is not disconnected, the secondelectrode CAT can be deposited on the emission layer EL in stable, theprofile of the second electrode CAT can have concaved shape at the areaoverlapping the trench TR.

Since the display shown in FIG. 6 can have the top emission type, thesecond electrode CAT can be made of a transparent conductive materialsuch as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) in order totransmit the light emitted from the emission layer EL toward the upperdirection. In addition, the second electrode CAT can be formed as havinga single-layer structure or multiple-layer structure.

The encapsulation layer ENC can be disposed on the second electrode CAT.The encapsulation layer ENC can be made of an inorganic material, anorganic material or a mixture of an inorganic material and an organicmaterial, and can be configured as a single layer or a multilayer. Thecolor filters can be disposed on the encapsulation layer ENC. The colorfilters can include a first color filter CFR representing red color Rallocated at the first sub-pixel P1, a second color filter CFGrepresenting green color G allocated at the second sub-pixel P2, and athird color filter CFB representing blue color B allocated at the thirdsub-pixel P3. For the first sub-pixel P1, only the red color R can betransmitted as the white color light passes through the first colorfilter CFR. For the second sub-pixel P2, only the green color G can betransmitted as the white color light passes through the second colorfilter CFG. For the third sub-pixel P3, only the blue color B can betransmitted as the white color light passes through the third colorfilter CFB.

Accordingly, in the first embodiment, by disconnecting the chargegeneration layer 422 at the boundary areas between the sub-pixels P1 toP3 using the trench TR disposed under the emission layer EL, the lateralleakage current flowing between the boundary areas of adjacentsub-pixels P1 to P3 can be blocked. In detail, the charge generationlayer 422 can have higher conductivity than the first stack 421 and thesecond stack 423. Specifically, since the N-type charge generation layerof the charge generation layer 422 can include metal material, it hashigher conductivity than the first stack 421 and the second stack 423.The electrical carriers can mainly flow through the charge generationlayer 422 between the sub-pixels P1 to P3, so the amounts of electricalcarriers through the second stack 423 can be very low. Therefore, byforming the charge generation layer 422 to be disconnected at the insideof the trench TR, it is possible to reduce the movement of theelectrical carriers between the sub-pixels P1 to P3 disposed adjacent toeach other, so that the occurrence of the lateral leakage current can beprevented or reduced.

Second Embodiment

In the above first embodiment, an electroluminescence display having astructure for preventing or reducing the lateral leakage current byforming a trench TR surrounding each pixel has been described. As thedensity of the pixels increases, the size of the pixels dependentlydecreases, and the distance between the pixels decreases. In theinstance of the pixel density is not high, for example, 1K PPI (PixelPer Inch) or less, the lateral leakage current between neighboringpixels along the X-axis direction that is turned on at the same timeaccording to the scan signal can be the main cause of image qualitydegradation. Accordingly, only with the vertical trench TRV extendingalong the Y-axis direction between the pixels can sufficiently preventor reduce deterioration of image quality due to the lateral leakagecurrent. However, when the pixel density is increased, for example, 1Kto 2K PPI, the lateral leakage current between pixels adjacent along theY-axis direction can cause the image quality degradation. As a result,it is necessary to have a structure in which a horizontal trench TRHextending along the X-axis direction is further added, so that imagequality deterioration due to the lateral leakage current can becompletely prevented, as explained in the first embodiment.

Furthermore, when the pixel density is much higher, for example, in theinstance of ultra-high resolution of 4K PPI or higher, the distancebetween pixels becomes very narrow, and the width of the trench must benarrowed also. Under this condition, a problem occurs in that the widthof the trench is widened at a portion where the horizontal trench TRHand the vertical trench TRV intersect.

When the width of the trench TR is widened where the horizontal trenchTRH and the vertical trench TRV intersect, the charge generation layerCF can be contacted with the cathode electrode CAT, so that the lightemitting diode can be defective. Therefore, by example, the width of thetrench TR is determined in consideration of the thickness of the firstemission layer E1, the charge generation layer CG and the secondemission layer E2 stacked on the anode electrode ANO, so that the firstemission layer E1 and the charge generation layer CG are disconnected bythe trench TR.

This will be explained in detail with reference to FIGS. 7 and 8 . FIG.7 is a plane view illustrating a structure of trench disposed between2×2 pixels in an electroluminescence display according to the firstembodiment of the present disclosure. FIG. 8 is a cross-sectional viewalong to cutting line II-II′ in FIG. 7 , for illustrating a structure ofan electroluminescence display according to the first embodiment of thepresent disclosure.

As shown in FIG. 7 , a description will be made based on a 2×2 matrixstructure. The first pixel P1 can be arranged in 1^(st) row and 1^(st)column, the second pixel P2 can be arranged in 1^(st) row and 2^(nd)column, the third pixel P3 can be arranged in 2^(nd) row and 1^(st)column, and the fourth pixel P4 can be arranged in 2^(nd) row and 2^(nd)column. The vertical trench TRV can be disposed between the first pixelP1 and the second pixel P2 and between the third pixel P3 and the fourthpixel P4. The horizontal trench TRH can be disposed between the firstpixel P1 and the third pixel P3 and between the second pixel P2 and thefourth pixel P4.

The vertical trench TRV and the horizontal trench TRH can have apredetermined width. In this instance, the etchant can be concentratedat the intersection portion CRO where the vertical trench TRV and thehorizontal trench TRH are crossing, so that the corner portions are overetched and a cross-trench TRO can be formed with wider width than thevertical trench TRV and the horizontal trench TRH.

With the condition in which the cross-trench TRO having a width widerthan those of the vertical trench TRV and the horizontal trench TRH, thefirst emission layer E1 can be deposited on the anode electrode ANO andthe bank BA. As the result, even though the first emission layer E1 canbe stacked on the bottom surface 10 of the cross-trench TRO, it can benot stacked on the side wall surface 20 and is stacked on the topsurface. The first emission layer E1 can be deposited on the wholesurface of the substrate 110, but the portions of the first emissionlayer E1 can be disconnected by the cross-trench TRO, so that the firstemission layer E1 can be separated in the pixels.

The charge generation layer CG can be deposited on the first emissionlayer E1. On the bottom surface 10 of the cross-trench TRO, the chargegeneration layer CG can be stacked on the first emission layer E1. Onthe side wall surface 20, the charge generation layer CG can cover thefirst emission layer E1 and can extend to the bottom of the side wallsurface 20. This can be caused by the width of the cross-trench TRObeing wider than those of the other trenches TRV and TRH. The chargegeneration layer CG can be deposited on the whole surface of thesubstrate 110, but the portions of the charge generation layer CG can bedisconnected by the cross-trench TRO, so that the charge generationlayer CG can be separated in the pixels.

The second emission layer E2 can be deposited on the charge generationlayer CG. On the bottom surface 10 of the cross-trench TRO, the secondemission layer E2 can be stacked on the charge generation layer CG. Asthe deposition process of the second emission layer E2 is performed, thesecond emission layer E2 becoming increasingly thicker from the leftpixel and the second emission layer E2 becoming increasingly thickerfrom the right pixel can cover the charge generation layer CG at theupper portion of the trench TR. However, the upper portion of thecross-trench TRO need not be closed and can be formed in an openstructure.

After that the cathode electrode CAT can be deposited on the secondemission layer E2. Since the cross-trench TRO is not closed or coveredby the second emission layer E2, the cathode electrode CAT can bedeposited along the open shaped profile of the cross-trench TRO so as tobe deposited on the side wall surface 20 and the bottom surface 10. Forexample, the cathode electrode CAT can have a deposited profileconnecting all pixels via the side-wall surface 20 and the bottomsurface 10 of the cross-trench TRO.

Under this structure, the cathode electrode CAT can directly contact theexposed charge generation layer CG on the side wall 20 of thecross-trench TRO. When the cathode electrode CAT and the chargegeneration layer CG are directly connected in this way, the normalstructure of the light emitting diode EL formed by the stacked structureof the anode electrode ANO, the organic emission layer EL and thecathode electrode CAT is not formed. Therefore, the light emitting diodeEL can be defective.

Hereinafter, referring to FIGS. 9 and 10 , the second embodiment whichis provided in order to prevent or reduce such a problem, will bedescribed. FIG. 9 is a plane view illustrating a structure of 2×2 pixelsin the electroluminescence display according to the second embodiment ofthe present disclosure. FIG. 10 is a cross-sectional view along tocutting line III-III′ in FIG. 9 , for illustrating a structure of anelectroluminescence display according to the second embodiment of thepresent disclosure.

As shown in FIG. 9 , shown are pixels arranged in a 2×2 matrix structureas an example. The first pixel P1 can be arranged in 1^(st) row and1^(st) column, the second pixel P2 can be arranged in 1^(st) row and2^(nd) column, the third pixel P3 can be arranged in 2^(nd) row and1^(st) column, and the fourth pixel P4 can be arranged in 2^(nd) row and2^(nd) column. Each pixel can have rectangular shape including a firstside 11, a second side 12 perpendicular to the first side 11, a thirdside 13 parallel to the first side 11 and a fourth side 14 parallel tothe second side 12. In embodiments of the present disclosure, a shape ofeach pixel need not be rectangular, and shapes including circular, ovalor polygonal can be provided.

The trenches TR are disposed outside a plurality of sides, such as thefour sides 11, 12, 13 and 14 of each pixel. The trench TR can include avertical trench TRV disposed between pixels adjacent along the X-axisdirection and a horizontal trench TRH disposed between pixels adjacentalong the Y-axis direction. The vertical trenches TRV can be notconnected as one body, but can have a separated line segment shape ineach pixel. The horizontal trenches TRH can have the same shape andstructure.

For example, a first vertical trench TRV1 can be disposed between thefirst pixel P1 and the second pixel P2, and a second vertical trenchTRV2 can be disposed between the third pixel P3 and the fourth pixel P4.Further, a first horizontal trench TRH1 can be disposed between thefirst pixel P1 and the third pixel P3, and a second horizontal trenchTRH2 can be disposed between the second pixel P2 and the fourth pixelP4.

The first vertical trench TRV1 and the second vertical trench TRV2 canhave a same predetermined width, and the lengths can be the same with orlittle longer than the corresponding vertical sides of the pixel. Thefirst horizontal trench TRH1 and the second horizontal trench TRH2 canhave a same predetermined width, and the lengths can be the same with orlittle longer than the corresponding horizontal sides of the pixel.

At the intersection portion where the first vertical trench TRV1, thesecond vertical trench TRV2, the first horizontal trench TRH1 and thesecond horizontal trench TRH2 meet each other, a protrusion pillar PRLcan be disposed. The protrusion pillar PRL can have a rectangular pillarshape in which a cross section has a quadrangular shape having foursides corresponding to the width of the trenches TR including thevertical trenches TRV and the horizontal trenches TRH. The protrusionpillar PRL can be made of an organic insulating material or an inorganicinsulating material. In embodiments of the present disclosure, a shapeof the protrusion pillar PRL need not be rectangular or cross shaped,but shapes including circular, oval or polygonal can be provided.

Referring to FIG. 10 , the emission layer EL can have the stackedstructure at the trench as explained in the first embodiment. Forexample, after forming the trench TR, the first emission layer E1 can bedeposited on the anode electrode ANO and the bank BA. On the bottomsurface 10 of the trench TR, the first emission layer E1 can bedeposited. On the side wall surface 20 of the trench TR, the firstemission layer E1 need not cover all of the side wall surface 20 but canbe stacked on top portions only. Therefore, the first emission layer E1can be deposited on the whole surface of the substrate 110, but theportions of the first emission layer E1 can be disconnected by trench TRin pixel unit.

The charge generation layer CG can be deposited on the first emissionlayer E1. The charge generation layer CG can be stacked on the bottomsurface 10 of the trench TR. On the side wall surface 20, the chargegeneration layer CG can be deposited only at the top portions.Accordingly, the charge generation layer CG can be deposited on thewhole surface of the substrate 110, but the portions of the chargegeneration layer CG can be disconnected by trench TR in pixel unit.

The second emission layer E2 can be deposited on the charge generationlayer CG. The second emission layer E2 thickened from the left side andthe second emission layer E2 thickened from the right side can contacteach other at the top portion of the trench TR, so that the upper spaceof the trench TR can be closed. As the result, the second emission layerE2 can have a structure in which the second emission layer E2 orportions can be connected over all pixels on the whole surface of thesubstrate 110.

The cathode electrode CAT can be deposited on the second emission layerE2. Since the second emission layer E2 has a structure connected betweenall pixels on the entire surface of the substrate 110, the cathodeelectrode CAT also has a structure connected between all pixels.

On the other hand, the trench TR is not formed at the intersectionportion CRO where the vertical trench TRV and the horizontal trench TRHintersect, but the protrusion pillar PRL stacked on the bank BA can beformed.

At the intersection portion CRO, the first emission layer E1 has astructure connected between the first pixel P1 and the fourth pixel P4which are diagonally adjacent to each other as riding over theprotrusion pillar PRL. However, due to the height of the protrusionpillar PRL, the first emission layer E1 can be deposited with athickness on the side wall of the protrusion pillar PRL that is thinnerthan a thickness of the first emission layer E1 on the bank BA or theanode electrode ANO.

The charge generation layer CG can be deposited on the first emissionlayer E1. The charge generation layer CG can have a structure connectedbetween the first pixel P1 and the fourth pixel P4 which are diagonallyadj acent to each other as riding over the protrusion pillar PRL.However, due to the height of the protrusion pillar PRL, the chargegeneration layer CG can be deposited with a thin thickness on the sidewall of the protrusion pillar PRL.

The second emission layer E2 can be deposited on the charge generationlayer CG. The second emission layer E2 can have a structure connectedbetween the first pixel P1 and the fourth pixel P4 which are diagonallyadj acent to each other as riding over the protrusion pillar PRL.However, due to the height of the protrusion pillar PRL, the secondemission layer E2 can be deposited with a thickness on the side wall ofthe protrusion pillar PRL that is thinner than a thickness of the secondemission layer E2 on the anode electrode ANO.

The cathode electrode CAT can be deposited on the second emission layerE2. The cathode electrode CAT can have a structure connected between thefirst pixel P1 and the fourth pixel P4 which are diagonally adjacent toeach other as riding over the protrusion pillar PRL. As the cathodeelectrode CAT can be made of inorganic material, the cathode electrodeCAT can have a thickness the same with other portions on the side wallsurface of the protrusion pillar PRL unlike the first emission layer E1,the charge generation layer CG and the second emission layer E2 whichare organic materials.

Like this, at the protrusion pillar PRL, both the emission layer EL andthe cathode electrode CAT can have a structure continuously connectedwithout being disconnected. However, for the charge generation layer CG,the electrical resistance at the portion connected between the firstpixel P1 and the fourth pixel P4 can have a very high value due to theheight of the protrusion pillar PRL. In particular, the chargegeneration layer CG is significantly thinner than the first emissionlayer E1 and the second emission layer E2, and is stacked much thinneron the side wall surface of the protrusion pillar PRL than at the bankBA, for example, furthermore, the area occupied by the protrusion pillarPRL is very small compared to the pixel area. Therefore, a portion ofthe charge generation layer CG that passes over the protrusion pillarPRL can have a very high resistance. As the result, even though thecharge generation layer CG can be physically connected between the firstpixel P1 and the fourth pixel P4, the electrical connectivity can be thedisconnected state.

Unlike the instance of the cross-trench TRO at the intersection portionCRO, the charge generation layer CG may not have a short circuit withthe cathode electrode CAT, so that light emitting diode EL can be formednormally always.

The bank BA can be formed with a double stacked structure. The bank BAcan define the emission area of the anode electrode ANO. In addition, inthis disclosure, the bank BA can be used as an element for forming thetrench TR. Therefore, according to the manufacturing process, the bankBA can be formed as a double layered structure. In this instance, thebank BA can include a first bank BA1 and the second bank BA2 that aresequentially stacked. The first bank BA1 and the second bank BA2 can bemade of other materials having different characteristics.

Third Embodiment

Hereinafter, referring to FIG. 11 , the third embodiment will bedescribed. FIG. 11 is a plane view illustrating a structure of 2×2pixels in the electroluminescence display according to the thirdembodiment of the present disclosure.

FIG. 11 can show the same structure with the FIG. 9 explaining thesecond embodiment. The different point is the shape of the protrusionpillar PRL. Therefore, the same explanation may not be duplicated if notrequired. The feature of the third embodiment is that the protrusionpillars PRL are formed at respective ends of the first vertical trenchTRV1, the second vertical trench TRV2, the first horizontal trench TRH1and the second horizontal trench TRH2, respectively. Further, having astructure protruding in the trench directions (i.e., in a lateraldirection), the rectangular pillar is changed into a ‘+’ shaped (or across shaped) pillar in a cross-sectional view.

For example, the lateral length of the protrusion pillar PRL protrudingtoward the first horizontal trench TRH1 from the portion facing thefirst horizontal trench TRH1 can be as small as possible. Similarly, ina portion where the protrusion pillar PRL faces each of the secondhorizontal trench TRH2, the first vertical trench TRV1 and the secondvertical trench TRV2, the lengths protruding toward each of the secondhorizontal trench TRH2, the first vertical trench TRV1 and the secondvertical trench TRV2 can be as small as possible, for example.

As explained in the second embodiment, the protrusion pillar PRL can bea structure that maintains the connectivity of the emission layer ELbetween neighboring pixels without breaking the connectivity of theemission layer EL. However, the protrusion pillar PRL can give the sameeffect as the electrical disconnection by increasing the resistance inthe structure that passes over the protruding pillar PRL. However, thiscan have a problem in which the resistance decreases as the area to beconnected increases. Therefore, when the area of the protrusion pillarPRL can be more increased, an electrical disconnection effect may not beobtained.

Therefore, in the instance that the protrusion pillar PRL can be a ‘+’shaped pillar, the length protruding in the lateral direction cansatisfy a condition that the emission layer EL overriding the protrusionpillar PRL can maintain high resistance. By example, as in the secondembodiment, the protrusion pillar PRL can have a rectangular pillarshape without a length protruding in the lateral direction for improvedperformance and/or ease of manufacture.

The description will be based on the first horizontal trench TRH1disposed on the fourth side 14 of the first pixel P1. The fourth side 14can have a horizontal length L14 of the pixel. A length of the firsthorizontal trench TRH1 can be defined as the trench length LTR. Inaddition, a length protruding from the protrusion pillar PRL toward thefirst horizontal trench TRH1 can be defined as the protrusion lengthLPR. The trench length LTR can have a length equal to or longer than thehorizontal length L14 of the pixel. FIG. 11 illustrates an instance inwhich the trench length LTR is longer than the horizontal length L14 ofthe pixel.

By example, the protrusion length LPR can be 10% or less of the trenchlength LTR. Even with a length longer than this, the maximum protrusionlength LPR preferably does not exceed the separation distance betweenthe trench and the pixel. When the protrusion length LPR is exceededthis maximum value, the resistance of the emission layer, particularlythe charge generation layer CG, which passes over the protrusion pillarPRL can be lowered, thereby the lateral leakage current can be occurredso causing the distortion in image quality.

By Example, the ratio of (the first protrusion length LPR1 protrudingfrom the protrusion pillar PRL disposed at one end of the firsthorizontal trench TRH1 toward the first horizontal trench TRH1) : (thelength of the first horizontal trench TRH1) : (the second protrusionlength LPR2 protruding from the protrusion pillar PRL disposed at theother end of the first horizontal trench TRH1 toward the firsthorizontal trench TRH1) can have any one of 1:8:1 to 0:10:0.

Fourth Embodiment

Hereinafter, referring to FIG. 12 , the fourth embodiment will beexplained. FIG. 12 is a cross-sectional view illustrating a structure ofan electroluminescence display according to the fourth embodiment of thepresent disclosure.

In the third embodiment, the protrusion pillar PRL disposed at thecorner portion of the pixel P may not cut the physical connectivity ofthe emission layer EL between neighboring pixels. In an instance offurther increased resolution, the size of the pixel can become smaller,and the size ratio of the corner portion with the pixel can increase. Inthis instance, with the structure described in the third embodiment, dueto the connectivity of the emission layer EL in the protrusion pillarPRL, the leakage current can slightly increase.

In order to prevent or reduce leakage current under this condition, itis possible to have a structure that cuts off the connectivity of theemission layer EL physically in the side wall surface of the protrusionpillar PRL.

Referring to FIG. 12 , after forming the trench TR, the first emissionlayer E1 can be deposited on the anode electrode ANO and the bank BA. Onthe bottom surface 10 of the trench TR, the first emission layer E1 canbe stacked. However, on the side-wall surface 20, the first emissionlayer E1 may not fully deposited, but it can be partially deposited atthe top portions of the trench TR. The first emission layer E1 can bedeposited on the surface of the substrate 110, but the electricalconnection of the first emission layer E1 can be cut, so that it can beseparated in pixel unit.

The charge generation layer CG is deposited on the first emission layerE1. On the bottom surface 10 of the trench TR, the charge generationlayer CG can be deposited on the first emission layer E1. On theside-wall surface 20, the charge generation layer CG can be partiallydeposited at the top portions. The charge generation layer CG can bedeposited on the surface of the substrate 110, but the electricalconnection of the charge generation layer CG can be cut, so that it canbe separated in pixel unit.

The second emission layer E2 is deposited on the charge generation layerCG. The second emission layer E2 thickened from the left side and thesecond emission layer E2 thickened from the right side can contact eachother at the top portion of the trench TR. Thus, a cross sectional shape(or profile) of the top space of the trench TR can be filled or closed.

After that, the cathode electrode CAT is deposited on the secondemission layer E2. Since the second emission layer E2 has a structureconnected between all pixels on the entire surface of the substrate 110,the cathode electrode CAT also has a structure connected between allpixels.

On the other hand, the trench TR is not formed at the intersectionportion CRO where the vertical trench TRV and the horizontal trench TRHintersect, but the protrusion pillar PRL stacked on the bank BA can beformed.

The cross-sectional shape of the protrusion pillar PRL formed at theintersection portion CRO can have a vertical tapered structure or areverse-tapered structure rather than a forward-tapered structure. Inthe instance of vertical taper structure, the length of the protrusionpillar PRL can be formed to be longer.

With this structure, the first emission layer E1 can have a structure inwhich it is disconnected from the side wall surface of the protrusionpillar PRL without riding over the protrusion pillar PRL. The chargegeneration layer CG can be deposited on the first emission layer E1. Thecharge generation layer CG can also have a structure that isdisconnected at the side wall surface of the protrusion pillar PRL. As aresult, even between the diagonally adjacent first pixel P1 and thefourth pixel P4 can be not connected but have a physically disconnectedstructure.

The second emission layer E2 can be deposited on the charge generationlayer CG. The second emission layer E2 can also have a structure that isdisconnected at the side wall surface of the protrusion pillar PRL.However, it is not limited thereto. For the second emission layer E2, itcan have the connection structure at the side wall surface of theprotrusion pillar PRL unlike the first emission layer E1 and the chargegeneration layer CG.

The cathode electrode CAT can be deposited on the second emission layerE2. Since the cathode electrode CAT can have an inorganic materialunlike the first emission layer E1, the charge generation layer CG andthe second emission layer E2 which are made of organic material, thecathode electrode CAT can have a structure connected between the firstpixel P1 and the fourth pixel P4 adjacent to each other in a diagonaldirection while passing over the protrusion pillar PRL. In someinstances, the cathode electrode CAT can have the disconnectionstructure at the side wall surface of the protrusion pillar PRL.

Even though the portions of the cathode electrode CAT can bedisconnected at the protrusion pillar PRL, since the cathode electrodeCAT can be connected between neighboring pixels in the trench TR region,the cathode electrode CAT can be connected through whole of thesubstrate 110.

In particular, unlike the instance of forming the trench TR at theintersection portion CRO, the charge generation layer CG may not have ashort circuit with the cathode electrode CAT, so that light emittingdiode EL can always be maintained in normal condition.

The features, structures, effects and so on described in the aboveexamples of the present disclosure are included in at least one exampleof the present disclosure, and are not limited to only one example.Furthermore, the features, structures, effects and the likes explainedin at least one example can be implemented in combination ormodification with respect to other examples by those skilled in the artto which this disclosure belongs. Accordingly, contents related to suchcombinations and variations should be construed as being included in thescope of the present disclosure.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the spirit or scope of the disclosures. Thus, itis intended that the present disclosure covers the modifications andvariations of this disclosure provided they come within the scope of theappended claims and their equivalents. These and other changes can bemade to the embodiments in light of the above-detailed description. Ingeneral, in the following claims, the terms used should not be construedto limit the claims to the specific embodiments disclosed in thespecification and the claims, but should be construed to include allpossible embodiments along with the full scope of equivalents to whichsuch claims are entitled. Accordingly, the claims are not limited by thedisclosure.

What is claimed is:
 1. An electroluminescence display comprising: asubstrate including a plurality of pixels, the plurality of pixelsincluding a first pixel at a first row and a first column, a secondpixel at the first row and a second column, a third pixel at a secondrow and the first column, and a fourth pixel at the second row and thesecond column; a first vertical trench extending in a first directionbetween the first pixel and the second pixel; a second vertical trenchextending in the first direction between the third pixel and the fourthpixel; a first horizontal trench extending in a second direction betweenthe first pixel and the third pixel; a second horizontal trenchextending in the second direction between the second pixel and thefourth pixel; and a protrusion pillar extending in a third direction atan intersection portion of the substrate where the first verticaltrench, the second vertical trench, the first horizontal trench, and thesecond horizontal trench converge.
 2. The electroluminescence displayaccording to claim 1, further comprising: a first emission layer havingportions at the first pixel, the second pixel, the third pixel and thefourth pixel, the portions of the first emission layer beingdisconnected at the first vertical trench, the second vertical trench,the first horizontal trench and the second horizontal trench, and beingconnected at the protrusion pillar; a charge generation layer on thefirst emission layer, and having portions that are disconnected at thefirst vertical trench, the second vertical trench, the first horizontaltrench and the second horizontal trench, and are connected at theprotrusion pillar; and a second emission layer on the charge generationlayer, and having portions connected at the first vertical trench, thesecond vertical trench, the first horizontal trench, the secondhorizontal trench, and the protrusion pillar.
 3. The electroluminescencedisplay according to claim 2, further comprising: a plurality of firstelectrodes, each of the plurality of first electrodes at the firstpixel, the second pixel, the third pixel and the fourth pixel; and asecond electrode disposed on the second emission layer, and havingportions connected over the first vertical trench, the second verticaltrench, the first horizontal trench, the second horizontal trench, andthe protrusion pillar.
 4. The electroluminescence display according toclaim 1, wherein the protrusion pillar has a rectangular shape includingfour sides corresponding to a width of the first vertical trench, thesecond vertical trench, the first horizontal trench and the secondhorizontal trench, respectively.
 5. The electroluminescence displayaccording to claim 4, wherein the protrusion pillar is a ‘+’ shapedpillar having protrusions with protruding lengths extending indirections of the first vertical trench, the second vertical trench, thefirst horizontal trench and the second horizontal trench, respectively.6. The electroluminescence display according to claim 5, wherein a ratioa protruding length from among the protruding lengths in a direction ofthe first vertical trench from the rectangular shape and a length of thefirst vertical trench has any one value selected from 1:8 to 0:10, andwherein a ratio of a protruding length from among the protruding lengthsin a direction of the first horizontal trench from the rectangular shapeand a length of the first horizontal trench in in a range of 1:8 to0:10.
 7. The electroluminescence display according to claim 1, furthercomprising: a plurality of first electrodes, each of the plurality offirst electrodes at the first pixel, the second pixel, the third pixel,and the fourth pixel, respectively; a first emission layer havingportions on the first pixel, the second pixel, the third pixel, and thefourth pixel, and the portions of the first emission layer beingdisconnected at the first vertical trench, the second vertical trench,the first horizontal trench, the second horizontal trench and theprotrusion pillar; a charge generation layer having portions on thefirst emission layer, and the portions of the charge generation layerbeing disconnected at the first vertical trench, the second verticaltrench, the first horizontal trench, the second horizontal trench andthe protrusion pillar; a second emission layer having portions on thecharge generation layer, and the portions of the second emission layerbeing connected over the first vertical trench, the second verticaltrench, the first horizontal trench, the second horizontal trench andthe protrusion pillar; and a second electrode having portions on thesecond emission layer, and the portions of the second electrode beingconnected over the first vertical trench, the second vertical trench,the first horizontal trench, the second horizontal trench and theprotrusion pillar.
 8. An electroluminescence display comprising: aplanarization layer on an entire surface of a substrate; a firstelectrode disposed on the planarization layer and including a firstside, a second side perpendicular to the first side, and an intersectionportion adjacent an intersection of the first side and the second side;a trench at a periphery of the first electrode and along the first sideand the second side, and having a predetermined width; a protrusionpillar disposed at the intersection portion; a first emission layerdisposed on the first electrode, and having portions disconnected at thetrench, and the portions of the first emission layer being connectedover the protrusion pillar; a charge generation layer disposed on thefirst emission layer, and having portions disconnected at the trench,and the portions of the charge generation layer being connected over theprotrusion pillar; a second emission layer disposed on the chargegeneration layer, and having portions connected over the trench, andconnected over the protrusion pillar; and a second electrode disposed onthe second emission layer, and having portions connected over the trenchand the pillar.
 9. The electroluminescence display according to claim 8,wherein the charge generation layer is electrically disconnected fromthe second electrode.
 10. The electroluminescence display according toclaim 8, wherein the first electrode further includes: a third sideparallel to the first side; and a fourth side parallel to the secondside, and wherein the trench includes: a first trench disposed at aperiphery of the first side and the third side; and a second trenchdisposed at a periphery of the second side and the fourth side.
 11. Theelectroluminescence display according to claim 10, further comprising: abank covering the first side, the second side, the third side and thefourth side of the first electrode, and exposing a central portion ofthe first pixel, wherein the trench is formed through the bank and intothe planarization layer with a predetermined depth.
 12. Theelectroluminescence display according to claim 11, wherein theprotrusion pillar is on an upper surface of the bank at the intersectionportion.
 13. The electroluminescence display according to claim 10,wherein the bank includes: a first bank; and a second bank on the firstbank.
 14. The electroluminescence display according to claim 8, whereinthe first electrode further includes: a third side parallel to the firstside; and a fourth side parallel to the second side, and wherein thetrench includes: a first trench at a periphery of the first side andcorresponding to the first side; a second trench at a periphery of thesecond side and corresponding to the second side; a third trench at aperiphery of the third side and corresponding to the third side; and afourth trench at a periphery of the fourth side and corresponding to thefourth side, wherein the protrusion pillar includes four sidescorresponding to the predetermined width of the trench at theintersection portion.
 15. The electroluminescence display according toclaim 10, wherein the protrusion pillar has a ‘+’ shaped pillarprotruding toward the first side and the second side from theintersection portion.
 16. The electroluminescence display according toclaim 10, wherein a ratio of a first protrusion length protruding fromthe protrusion pillar at one end of the first trench toward the firsttrench : a length of the first trench : a second protrusion lengthprotruding from the protrusion pillar disposed at another other end ofthe first trench toward the first trench is in a range of 1:8:1 to0:10:0.
 17. An electroluminescence display comprising: a planarizationlayer on a substrate; a first electrode on the planarization layer, andincluding a first side, a second side perpendicular to the first side,and an intersection portion at a crossing of the first side and thesecond side; a trench at a periphery of the first side and the secondside, and having a predetermined width; a protrusion pillar at aperiphery of the intersection portion; a first emission layer on thefirst electrode, and having portions disconnected at the trench and theprotrusion pillar; a charge generation layer on the first emissionlayer, and having portions disconnected at the trench and the protrusionpillar; a second emission layer on the charge generation layer; and asecond electrode on the second emission layer, and having portionsconnected over the trench and the protrusion pillar.
 18. Theelectroluminescence display according to claim 17, wherein the portionsof the second emission layer are connected over the trench, and aredisconnected at the protrusion pillar.
 19. The electroluminescencedisplay according to claim 17, wherein the portions of the secondemission layer are connected over the trench and the protrusion pillar.20. The electroluminescence display according to claim 2, furthercomprising a void present in at least one of the first vertical trench,the second vertical trench, the first horizontal trench, and the secondhorizontal trench, wherein the void is covered by the second emissionlayer.